1. Field of the Invention
The present invention relates to a double side action type reciprocating compressor, and more particularly, to a double side action type reciprocating compressor including a suction/discharge system, which is suitable for manufacturing the compressor to be extremely small.
2. Description of the Background Art
In general, a double side action type reciprocating compressor is a high efficiency and low vibration compressor, where two compression units are combined with the respective reciprocating motors and are arranged to face each other in a casing.
As shown in FIG. 1, the conventional double side action type reciprocating compressor includes a cylindrical casing 10 including a suction pipe (SP) and a discharge pipe (DP) on both sides in a radial direction, a first reciprocating motor 21 and a second reciprocating motor 22 loaded on both sides inside the casing 10 in a longitudinal direction, a cylinder 30 loaded between the two reciprocating motors 21 and 22 in a long diameter direction, a first piston 41 and a second piston 42 inserted into both sides of the cylinder 30 to slide in a direction of a long diameter so that the respective leading ends of the first and second pistons 41 and 42 face each other and combined with moving magnets 21B and 22B of the reciprocating motors 21 and 22, a first suction valve assembly 51 and a second suction valve assembly 52 respectively combined with the leading ends of the pistons 41 and 42 so as to face each other, and a first discharge valve 61 and a second discharge valve 62 loaded so as to open and close the discharge side of the cylinder 30.
The cylinder 30 is ring-shaped and includes a through hole 31 in a reciprocating direction of the pistons 41 and 42 so that the pistons 41 and 42 are inserted into the cylinder 30 to slide, to thus form compression spaces S1 and a discharge space S2. A suction passage 32 whose section is T-shaped is formed on one side outer circumference so that the outlet end of the suction passage 32 is connected to suction passages 41a and 42a of the pistons 41 and 42 through an inner space of the casing 10. A discharge passage 33 whose inlet end is connected to the discharge space S2 and whose section is I-shaped is formed on the opposite side outer circumference.
The first piston 41 and the second piston 42 are combined with the moving magnets 21B and 22B of the first reciprocating motor 21 and the second reciprocating motor 22. The suction passages 41a and 42a are penetratingly formed in a reciprocating motion direction of the motors 21 and 22 in the middle of the pistons 41 and 42.
As shown in FIG. 3, the first suction valve assembly 51 and the second suction valve assembly 52 include a first valve housing 51A and a second valve housing 52A including suction holes 51a and 52a connected to the suction passages 41a and 42a of the pistons 41 and 42 and fit-pressingly fixed to the leading ends of the pistons 41 and 42 and a first suction valve 51B and a second suction valve 52B inserted into the inner space of the valve housings 51A and 52A to slide, the first suction valve 51B and the second suction valve 52B for selectively opening and closing the suction passages 41a and 42a of the pistons 41 and 42 and the suction holes 51a and 52a of the valve housings 51A and 52A according to the reciprocating motion of the pistons 41 and 42.
The first discharge valve 61 and the second discharge valve 62 are installed between the compression spaces S1 and the discharge space S2 so as to open and close the compression spaces S1 of the cylinder 30. The pressure back surfaces of the discharge valves 61 and 62 are supported by a valve spring 63.
Among reference numerals that are not described, 21A and 22A are a first stator and a second stator and 71 and 72 are a first resonance spring and a second resonance spring.
The operation of the conventional double side action type reciprocating compressor will now be described.
When power is applied to the reciprocating motors 21 and 22, the pistons 41 and 42 are in a linear reciprocating motion in the through hole 31 of the cylinder 30 and a refrigerant gas is received into both side suction pressure regions (not shown), that is, the space inside the casing 10 along the suction pipe (SP) and the suction passage 32 of the cylinder 30.
The refrigerant gas is received into the compression spaces S1 of the cylinder 30 along the suction passages 41a and 42a of the pistons 41 and 42 and is compressed, and then is discharged to the discharge space S2 due to the continuous reciprocating motion of the first piston 41 and the second piston 42. The compressed gas of the discharge space S2 is discharged to a system outside the casing 10 through the discharge passage 33 and the discharge pipe (DP) during the next discharge stroke of the pistons 41 and 42.
To be more specific, as shown in FIG. 2, when the pistons 41 and 42 move to be far from each other, the refrigerant gas filled in the suction pressure regions of the casing 10 is sucked up into the compression spaces S1 of the cylinder 30 through the suction passages 41a and 42a while pushing the suction valves 51B and 52B of the pistons 41 and 42. At this time, because the pressure of the compression spaces S1 is lower than the pressure of the suction space, such as a suction pipe (SP) and an interior of the case 10, the first discharge valve 61 and the second discharge valve 62 close the discharge side of the cylinder 30.
As shown in FIG. 3, when the pistons 41 and 42 move to be closer to each other, the pressure of the compression spaces S1 becomes higher than the pressure of the discharge space S2. Accordingly, the discharge valves 61 and 62 that fill up the compression spaces S1 of the cylinder 30 are opened. At the same time, the compressed refrigerant gas is received into the discharge space S2. Accordingly, the compressed refrigerant gas of the discharge space S2 is discharged to the outside of the compressor. At this time, the suction valve 51B fills up the suction passages 41a and 42a of the pistons 41 and 42 because the pressure of the compression spaces S1 is higher than the pressure inside the casing 10.
However, according to the conventional double side action type reciprocating compressor, when the suction passages 41a and 42a are formed in the pistons 41 and 42 and the suction valve assemblies 51 and 52 are loaded in the ends of the suction passages 41a and 42a or when the suction valve assemblies 51 and 52 are loaded in the leading ends of the pistons 41 and 42, it is difficult to manufacture the suction valve assemblies 51 and 52 suitable for the pistons 41 and 42 having a small diameter and to load the suction valves 51B and 52B in the pistons 41 and 42. Accordingly, productivity deteriorates. Also, during the reciprocating motion of the pistons 41 and 42, the suction valve assemblies 51 and 52 collide with the first discharge valve 61 and the second discharge valve 62 or deviate from the pistons 41 and 42. Accordingly, the suction valve assemblies 51 and 52 can be damaged.
Also, according to the characteristics of the compressor, the pistons 41 and 42 that are moving objects must be precisely processed. Portions to be precisely processed such as a valve settling place increase in the pistons 41 and 42. As a result, it is more difficult to process the pistons 41 and 42.
Also, because the discharge valve assemblies 51 and 52 are positioned in front of the pistons 41 and 42, the length of the entire apparatus becomes longer.
Also, because the plurality of compression spaces S1 exist and the respective compression spaces S1 are opened and closed by the linear reciprocating motion of the pistons 41 and 42 combined with the motors 21 and 22, when there is something wrong with the electrical control of the motors 21 and 22, the pressures of the compressed compression spaces S1 become unbalanced. So, the motion of the compressor would be unstable. Accordingly, from side to side vibration of the compression apparatus is accelerated.